Conventionally, a card reader structured to read magnetic data recorded on a card and/or to record magnetic data on a card has been widely utilized. In an industry of the financial institutions and the like where the card reader is utilized, conventionally, a so-called skimming has become a serious problem in which a criminal attaches a magnetic head to a card insertion part of the card reader to illegally acquire magnetic data of a card by using the magnetic head. In order to prevent the problem, a card reader has been proposed which is provided with a metal sensor for detecting a magnetic head for skimming (hereinafter, referred to as a “skimming magnetic head”) which is attached to a front face side of a card insertion part (see, for example, Japanese Patent Laid-Open No. 2013-37555).
In the card reader described in the above-mentioned Patent Literature, the metal sensor is disposed in an inside of the card insertion part which is formed in a hollow shape. Further, the metal sensor includes a core which is formed of magnetic material and a pair of excitation coils and a detection coil which are wound around the core. In the card reader, when a foreign matter including metal material is detected by the metal sensor, a predetermined abnormality processing is executed and reading of magnetic data by the skimming magnetic head attached to the front face side of the card insertion part can be prevented.
A trick for skimming by a criminal has become skillfully year by year and a situation has occurred such that a device for skimming (hereinafter, referred to as a “skimming device”) such as a skimming magnetic head for reading magnetic data of a card is attached to an inside of the card reader where a skimming device has not been conventionally attached. In the card reader described in the above-mentioned Patent Literature, a skimming device attached to a front face side of a card insertion part can be detected by a metal sensor. However, the metal sensor is unable to detect a skimming device which is attached inside the card reader. Therefore, in the card reader, when a skimming device is attached to an inside of the card reader, reading of magnetic data by the skimming device cannot be prevented.
Even when a skimming device is attached to an inside of the card reader, an outward appearance of the card reader is not changed and thus it is hard to be noticed that the skimming device has been attached to the card reader. Therefore, if a skimming device is attached to an inside of a card reader, a possibility that skimming is performed for a long term is increased and thus serious damage may be suffered.